This proposal seeks to identify and study the regulation of specific postsynaptic components on chick parasympathetic ciliary ganglion neurons, focusing on the neuronal nicotinic acetylcholine receptor. Monoclonal antibodies raised against muscle and electric organ acetylcholine receptor will be screened for cross reaction with ciliary ganglion neurons. The surface distribution of the identified cross reacting antibodies will be determined in ultrastructural studies. Preganglionic denervation and postganglionic axotomy in vivo and changes in the growth medium in culture will be used to modulate levels of acetylcholine sensitivity for correlative studies on amount and distribution of antibody binding to putative receptor. Immunocryoultramicrotomy will be used to visualize the intracellular pathways of synthesis, assembly, and transport of acetylcholine receptors both in a model system, the BC3H-1 muscle cell line, and in chick ciliary ganglion neurons in cell culture and in vivo. Affinity purified antibodies together with immunocryoultramicrotomy will be used to identify cytoskeletal elements associated with postsynaptic structures in the neurons. The temporal and spatial relationship of specific synaptic antigens will be followed through development and in response to denervation and axotomy. These studies will help determine whether the organization of synaptic components and the regulation of acetylcholine receptors that occurs at the neuromuscular junction can be extended to nerve-nerve synapses. New regulatory features and structural components are likely to be identified as well.